Microscope systems of this kind that work with analog video cameras or modern digital cameras, and corresponding image production methods, are known from the existing art. They are used to display high-resolution microscope images or to display, for example, biological processes in real time, or to observe manipulations of various types of specimens. Analog video cameras were and are in principle capable of generating a moving image (usually at a standard of 25 or 30 frames per second), but their resolution is limited (usually 640×480 pixels as standard). Analog video cameras are consequently not suitable for demanding tasks or for documentation purposes. They are equally unsuitable for very low luminance specimens (e.g. in fluorescence investigations), since the predetermined frame rate does not allow long exposure times.
Modern digital cameras for microscopy, on the other hand, generate images of good quality and resolution and moreover allow long exposure times. It is not readily possible, however, to work interactively at the microscope with such cameras. Interactive work at the microscope often involves searching for a specific specimen point, focusing on it, and then possibly performing manipulations or investigations. Because of the large volumes of data for each image, perceptible delays (in the range from 1/10 of a second to several seconds) occur upon readout from the sensor and upon transfer to the processing computer or the screen.
Most of these digital cameras possess a plurality of adjustment capabilities allowing operation in a variety of image modes. For a good image of low luminance specimens, for example, the exposure time must be increased to several seconds; this correspondingly limits the frame rate. It is also possible to shorten the exposure time and correspondingly increase the camera's internal gain. This results, however, in a noisy and unattractive image that can be used for navigation purposes (detail searching) but not for documentation purposes. Another capability is that of selecting different image processing modes. For example, pixel groups can be grouped together or “binned” into pixel groups (e.g. 2×2, 3×3, etc.) when the images are read out. With so-called “subsampling”, only every second or third pixel is read out. This yields images that have less detail but are available at a higher frame rate. The camera's internal gain and the above-described image processing modes can also be combined with one another.
To ensure that specimens look as sharp as possible while they are being displaced (“navigation”), the exposure time must be decreased to approximately one to two milliseconds, regardless of the frame repetition rate. This results, even with specimens that are not low-luminance, in a situation like the one already described above: for usable images the internal gain must be raised, but this causes image noise to increase.
Lastly, the images generated in the camera's various image modes generally differ in terms of size (especially if the image modes differ in terms of resolution), and often in terms of brightness and color. This is not a convenient solution for the person viewing the screen.